Image sensors

ABSTRACT

Image sensors are provided. An image sensor includes a semiconductor substrate including a pixel region. The image sensor includes first and second photoelectric conversion elements in the pixel region. The image sensor includes an isolation region between the first and second photoelectric conversion elements. The isolation region is off-center with respect to the pixel region.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of and claimspriority from U.S. patent application Ser. No. 15/605,076, filed May 25,2017, which claims priority under 35 U.S.C. § 119 to Korean PatentApplication No. 10-2016-0101461, filed Aug. 9, 2016, in the KoreanIntellectual Property Office, the disclosures of which are herebyincorporated by reference herein in entirety.

BACKGROUND

The present disclosure relates to image sensors. An image sensorconverts an optical image into an electrical signal. As computer andcommunication industries have developed, high-performance image sensorshave been increasingly demanded in various fields such as a digitalcamera, a camcorder, a personal communication system (PCS), a gameconsole, a security camera, and a medical micro camera. Thus, it may bebeneficial to increase or improve performance of an imaging apparatus oran image sensor included in the imaging apparatus.

SUMMARY

Example embodiments of present inventive concepts may provide an imagesensor having an improved optical characteristic.

An image sensor, according to some embodiments, may include asemiconductor substrate including a first pixel region and a secondpixel region. The image sensor may include a first isolation structurein the semiconductor substrate to define the first and second pixelregions. The image sensor may include a first photoelectric conversionelement and a second photoelectric conversion element in each of thefirst and second pixel regions. The image sensor may include a secondisolation structure between the first and second photoelectricconversion elements in the first pixel region. The image sensor mayinclude an isolation dopant region between the first and secondphotoelectric conversion elements in the second pixel region. A centerof the second isolation structure may be shifted relative to a center ofthe first pixel region when viewed from a plan view. The first pixelregion may be one of a plurality of first pixel regions, and the secondpixel region may be one of a plurality of second pixel regions. Thefirst pixel regions and the second pixel regions may be alternatelyarranged along a first direction.

An image sensor, according to some embodiments, may include asemiconductor substrate including a pixel region. The image sensor mayinclude a micro lens on the pixel region. The image sensor may include afirst isolation structure in the semiconductor substrate to define thepixel region. The image sensor may include a first photoelectricconversion element and a second photoelectric conversion element in thepixel region. The image sensor may include a second isolation structurebetween the first and second photoelectric conversion elements in thepixel region. A center of the micro lens may be shifted from a center ofthe pixel region when viewed from a plan view. A center of the secondisolation structure may be shifted from the center of the pixel regionwhen viewed from a plan view.

An image sensor, according to some embodiments, may include asemiconductor substrate that includes a first pixel region in a firstregion and a second pixel region in a second region. The image sensormay include a first isolation structure in the semiconductor substrateto define the first and second pixel regions. The image sensor mayinclude a first photoelectric conversion element and a secondphotoelectric conversion element in each of the first and second pixelregions. The image sensor may include a second isolation structurebetween the first and second photoelectric conversion elements in thefirst pixel region. The image sensor may include a third isolationstructure between the first and second photoelectric conversion elementsin the second pixel region. The first region may be at a center of thesemiconductor substrate. The first region may be spaced apart from thesecond region in a first direction. A center of the second isolationstructure may be substantially aligned with a center of the first pixelregion when viewed from a plan view. Moreover, a center of the thirdisolation structure may be shifted from a center of the second pixelregion in the first direction when viewed from a plan view.

An image sensor, according to some embodiments, may include asemiconductor substrate including a plurality of pixel regions. Theimage sensor may include first and second photoelectric conversionregions in one of the plurality of pixel regions. The image sensor mayinclude an isolation region extending in the semiconductor substratebetween the first and second photoelectric conversion regions in the oneof the plurality of pixel regions. The image sensor may include a lensthat overlaps a center of the isolation region. The center of theisolation region and a center of the lens may be offset from a center ofthe one of the plurality of pixel regions.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

FIG. 1 is a schematic block diagram illustrating an image sensoraccording to some embodiments of present inventive concepts.

FIG. 2 is a schematic circuit diagram illustrating an active pixelsensor array of an image sensor according to some embodiments of presentinventive concepts.

FIG. 3 is a circuit diagram illustrating an active pixel sensor array ofan image sensor according to some embodiments of present inventiveconcepts.

FIGS. 4A, 4B, 4C and 4D are plan views illustrating color filter arraysof image sensors according to some embodiments of present inventiveconcepts.

FIG. 5A is a plan view illustrating an image sensor according to someembodiments of present inventive concepts.

FIG. 5B is a cross-sectional view taken along a third direction D3 ofFIG. 5A.

FIGS. 6 and 8 are plan views illustrating an image sensor according tosome embodiments of present inventive concepts.

FIGS. 7A, 7B, and 7C are cross-sectional views taken along lines I-I′,and of FIG. 6, respectively.

FIGS. 9A and 9B are cross-sectional views taken along lines I-I′ andII-II′ of FIG. 8, respectively.

FIG. 10 is an enlarged plan view of a region ‘M’ of FIG. 8.

FIGS. 11 and 12 are plan views illustrating image sensors according tosome embodiments of present inventive concepts.

FIGS. 13 to 18 are cross-sectional views illustrating image sensorsaccording to some embodiments of present inventive concepts.

FIGS. 19 and 20 are plan views illustrating an image sensor according tosome embodiments of present inventive concepts.

FIG. 21 is a cross-sectional view taken along a line I-I′ FIG. 20.

FIGS. 22 and 23 are plan views illustrating an image sensor according tosome embodiments of present inventive concepts.

FIG. 24 is a cross-sectional view taken along a line I-I′ FIG. 23.

DETAILED DESCRIPTION

FIG. 1 is a schematic block diagram illustrating an image sensoraccording to some embodiments of the inventive concepts.

Referring to FIG. 1, an image sensor may include an active pixel sensorarray 1, a row decoder 2, a row driver 3, a column decoder 4, a timinggenerator 5, a correlated double sampler (CDS) 6, an analog-to-digitalconverter (ADC) 7, and an input/output (I/O) buffer 8.

The active pixel sensor array 1 may include a plurality of unit pixelstwo-dimensionally arranged and may convert optical signals intoelectrical signals. The active pixel sensor array 1 may be driven by aplurality of driving signals (e.g., a pixel selection signal, a resetsignal, and a charge transfer signal) provided from the row driver 3. Inaddition, the converted electrical signals may be provided to thecorrelated double sampler 6.

According to some embodiments of the inventive concepts, the imagesensor may perform an auto-focusing operation by phase differencedetection of light incident on the active pixel sensor array 1. Each ofthe unit pixels of the active pixel sensor array 1 may output a focussignal corresponding to a phase difference between lights incident on apair of photoelectric conversion elements. To perform the auto-focusingoperation, the focus signal may be used as a signal that adjusts aposition of a lens of an imaging apparatus including the image sensor.

The row driver 3 may provide a plurality of driving signals for drivinga plurality of unit pixels to the active pixel sensor array 1 inresponse to signals decoded in the row decoder 2. When the unit pixelsare arranged in a matrix form, the driving signals may be provided toeach row of the matrix.

The timing generator 5 may provide timing signals and control signals tothe row decoder 2 and the column decoder 4.

The correlated double sampler 6 may receive electrical signals generatedfrom the active pixel sensor array 1 and may hold and sample thereceived electrical signals. The correlated double sampler 6 may doublysample a specific noise level and a signal level of the electricalsignal to output a difference level corresponding to a differencebetween the noise level and the signal level.

The analog-to-digital converter 7 may convert an analog signal, whichcorresponds to the difference level outputted from the correlated doublesampler 6, into a digital signal.

The I/O buffer 8 may latch the digital signals and may sequentiallyoutput the latched digital signals to an image signal processing part inresponse to signals decoded in the column decoder 4.

FIG. 2 is a schematic circuit diagram illustrating an active pixelsensor array of an image sensor according to some embodiments of presentinventive concepts.

Referring to FIG. 2, an active pixel sensor array 1 may include aplurality of unit pixels P two-dimensionally arranged along rows andcolumns. An electrical signal may be generated by incident light in eachof the unit pixels P. The unit pixels P may be driven by driving signalstransmitted through a pixel selection line SEL, a charge transfer lineTx, and a reset line Rx which are connected to the unit pixels P. Inaddition, the electrical signals converted in the unit pixels P may beprovided to a control circuit through output lines Vout.

FIG. 3 is a circuit diagram illustrating an active pixel sensor array ofan image sensor according to some embodiments of present inventiveconcepts.

Referring to FIG. 3, an active pixel sensor array 1 may include aplurality of unit pixels P. The unit pixels P may be arranged in amatrix form along a row direction and a column direction. Each unitpixel P may include first and second photoelectric conversion elementsPD1 and PD2, first and second transfer transistors TX1 and TX2, andlogic transistors RX, SX, and DX. Here, the logic transistors mayinclude a reset transistor RX, a selection transistor SX, and a drivetransistor or source follower transistor DX. Gate electrodes of thefirst and second transfer transistors TX1 and TX2, a gate electrode ofthe reset transistor RX, and a gate electrode of the selectiontransistor SX may be connected to driving signal lines TG1, TG2, RG, andSG, respectively.

The first transfer transistor TX1 may include a first transfer gate TG1and the first photoelectric conversion element PD1, and the secondtransfer transistor TX2 may include a second transfer gate TG2 and thesecond photoelectric conversion element PD2. In addition, the first andsecond transfer transistors TX1 and TX2 may share a charge detectionnode (i.e., a floating diffusion region) FD.

The first and second photoelectric conversion elements PD1 and PD2 maygenerate and accumulate photocharges in proportion to the amount oflight incident on the active pixel sensor array 1. Each of the first andsecond photoelectric conversion elements PD1 and PD2 may include aphotodiode, a photo transistor, a photo gate, a pinned photodiode (PPD),or any combination thereof.

The first and second transfer gates TG1 and TG2 may transfer charges,which are accumulated in the first and second photoelectric conversionelements PD1 and PD2, into the charge detection node (i.e., the floatingdiffusion region) FD. Signals which are complementary to each other maybe applied to the first and second transfer gates TG1 and TG2. In otherwords, charges may be transferred from one of the first and secondphotoelectric conversion elements PD1 and PD2 into the charge detectionnode FD.

The charge detection node FD may receive the charges generated in thefirst and second photoelectric conversion elements PD1 and PD2 and maycumulatively store the received charges. The drive transistor DX may becontrolled according to the amount of the photocharges accumulated inthe charge detection node FD.

The reset transistor RX may periodically reset the charges accumulatedin the charge detection node FD. In detail, a drain electrode of thereset transistor RX may be connected to the charge detection node FD,and a source electrode of the reset transistor RX may be connected to apower voltage VDD. When the reset transistor RX is turned-on, the powervoltage VDD connected to the source electrode of the reset transistor RXmay be transmitted to the charge detection node FD. Thus, the chargesaccumulated in the charge detection node FD may be discharged to resetthe charge detection node FD when the reset transistor RX is turned-on.

The drive transistor DX and a constant current source may constitute asource follower buffer amplifier. The constant current source may bedisposed outside the unit pixel PX. The drive transistor DX may amplifya potential variation of the charge detection node FD and may providethe amplified potential variation to the output line Vout.

The selection transistor SX may select the unit pixels P of a row to besensed. When the selection transistor SX is turned-on, the power voltageVDD connected to a drain electrode of the drive transistor DX may betransmitted to a drain electrode of the selection transistor SX.

FIGS. 4A to 4D are plan views illustrating color filter arrays of imagesensors according to some embodiments of present inventive concepts.

Referring to FIG. 4A, in an active pixel sensor array 1, color filtersmay be disposed to correspond to the unit pixels, respectively. Each ofthe unit pixels may include one of red, green, and blue color filters R,G, and B. In other words, the unit pixels may include red pixelsincluding the red color filters R, blue pixels including the blue colorfilters B, and green pixels including the green color filters G. The redcolor filter R may transmit red light among visible light in the redpixel, and the photoelectric conversion element of the red pixel maygenerate photoelectrons corresponding to the red light. The blue colorfilter B may transmit blue light among visible light in the blue pixel,and the photoelectric conversion element of the blue pixel may generatephotoelectrons corresponding to the blue light. The green color filter Gof the green pixel may transmit green light among visible light, and thephotoelectric conversion element of the green pixel may generatephotoelectrons corresponding to the green light. Meanwhile, in someembodiments, the unit pixels of the active pixel sensor array 1 mayinclude magenta (Mg), yellow (Y), and cyan (Cy) color filters.

In some embodiments, the color filters R, G, and B may be arranged in aBayer pattern type in which the number of the green color filters G istwo times more than the number of the red color filters R or the numberof the blue color filters B. The color filters R, G, and B arranged in a2×2 matrix form may constitute one color filter group in the Bayerpattern. The Bayer pattern may include a plurality of the color filtergroups. Each of the color filter groups may include two green colorfilters G arranged in a diagonal direction, and red and blue colorfilters R and B arranged in another diagonal direction. In other words,each of the red and blue color filters R and B may be disposed betweenthe green color filters G adjacent to each other in the Bayer pattern.The color filter groups of the Bayer pattern may be repeatedly arrangedin a first direction D1 and a second direction D2.

Referring to FIG. 4B, each of unit pixels of an active pixel sensorarray 1 may include one of red, greed, blue, and white color filters R,G, B, and W. In some embodiments, the white color filter W may be atransparent color filter transmitting light of a visible wavelengthband. The red, green, blue, and white color filters R, G, B, and W maybe arranged in a 2×2 matrix form to constitute one color filter group,and a plurality of the color filter groups may be repeatedly arranged ina first direction D1 and a second direction D2.

Referring to FIG. 4C, an active pixel sensor array 1 may include colorpixels and depth pixels. Each of the color pixels may include one ofred, green, and blue color filters R, G, and B. Each of the depth pixelsmay include an infrared filter Z filtering infrared light.

The red, green, and blue color filters R, G, and B and the infraredfilter Z may be arranged in a 2×2 matrix form to constitute one filtergroup, and a plurality of the filter groups may be repeatedly arrangedin a first direction D1 and a second direction D2. In some embodiments,the depth pixel including the infrared filter Z may be disposed betweenadjacent two of the color pixels including the color filters R, G, andB. Areas of the unit pixels including the filters R, G, B, and Z may besubstantially equal to each other.

In each of the filter groups, lights of which wavelength bands aredifferent from each other may be incident on the unit pixels R, G, B,and Z. As described above, the color pixels may filter visible light togenerate photoelectrons. The infrared filter Z of the depth pixel maytransmit infrared light, and the photoelectric conversion element of thedepth pixel may generate photoelectrons corresponding to the infraredlight. The depth pixels may sense the infrared light to detect adistance between an imaging apparatus and a subject, and athree-dimensional image may be realized using the depth pixels.

Referring to FIG. 4D, an active pixel sensor array 1 may include colorpixels and depth pixels. Each of the color pixels may include one ofred, green, and blue color filters R, G, and B, and each of the depthpixels may include an infrared filter Z. The color pixels may bearranged along a first direction D1 and a second direction D2 and may bedisposed around the depth pixel. An area of the depth pixel includingthe infrared filter Z may be greater than an area of each of the colorpixels including the color filters R, G, and B.

FIG. 5A is a plan view illustrating an image sensor according to someembodiments of present inventive concepts, and FIG. 5B is across-sectional view taken along a third direction D3 of FIG. 5A.

Referring to FIGS. 5A and 5B, an image sensor according to someembodiments of present inventive concepts may include a semiconductorsubstrate 100 and a module lens ML disposed on or above thesemiconductor substrate 100. The module lens ML may be aligned with acenter of the semiconductor substrate 100 when viewed from a plan view.The active pixel sensor array described above with reference to FIGS. 1to 3 may be formed on the semiconductor substrate 100. The active pixelsensor array formed on the semiconductor substrate 100 will be describedlater in more detail.

Meanwhile, the semiconductor substrate 100 may include a first region R1and a second region R2. The first region R1 may be disposed at thecenter of the semiconductor substrate 100, and the second region R2 maybe spaced apart from the center of the semiconductor substrate 100. Indetail, the center (i.e., the first region R1) of the semiconductorsubstrate 100 may be spaced apart from the second region R2 in a thirddirection D3. In other words, a center CR1 of the first region R1 may bespaced apart from a center CR2 of the second region R2 in the thirddirection D3.

Light LI transmitted through the module lens ML may be incident on theactive pixel sensor array of the semiconductor substrate 100. Firstlight LI1 incident on the first region R1 may have a first incidentangle θ1 that is a substantially right angle. This is because the firstregion R1 is disposed at the center of the semiconductor substrate 100.Meanwhile, second light LI2 incident on the second region R2 may have asecond incident angle θ2. The second incident angle θ2 may be smallerthan the first incident angle θ1. This is because the second region R2is spaced apart from the center of the semiconductor substrate 100.

FIGS. 6 and 8 are plan views illustrating an image sensor according tosome embodiments of present inventive concepts. FIG. 6 is an enlargedplan view of the first region R1 of FIG. 5A, and FIG. 8 is an enlargedplan view of the second region R2 of FIG. 5A. FIGS. 7A, 7B, and 7C arecross-sectional views taken along lines I-I′, II-II′, and III-III′ ofFIG. 6, respectively. FIGS. 9A and 9B are cross-sectional views takenalong lines I-I′ and II-II′ of FIG. 8, respectively. FIG. 10 is anenlarged plan view of a region ‘M’ of FIG. 8. First, the first region R1of FIG. 5A will be described in more detail with reference to FIGS. 6and 7A to 7C.

Referring to FIGS. 6 and 7A to 7C, an image sensor according to someembodiments of present inventive concepts may include a photoelectricconversion layer 10, an interconnection layer 20, and a lighttransmission layer 30. The photoelectric conversion layer 10 may bedisposed between the interconnection layer 20 and the light transmissionlayer 30 in a cross-sectional view. For example, the semiconductorsubstrate 100 may have a first surface (or a front surface) 100 a and asecond surface (or a back surface) 100 b which are opposite to eachother. In some embodiments, the interconnection layer 20 may be disposedon the first surface 100 a of the semiconductor substrate 100, and thelight transmission layer 30 may be disposed on the second surface 100 bof the semiconductor substrate 100.

The photoelectric conversion layer 10 may include the semiconductorsubstrate 100 and first and second photoelectric conversion regions 110a and 110 b provided in the semiconductor substrate 100. Light incidentfrom the outside (i.e., from outside of the active pixel sensor array 1)may be converted into electrical signals in the first and secondphotoelectric conversion regions 110 a and 110 b.

The interconnection layer 20 may include logic transistors (see TX1,TX2, RX, DX, and SX of FIG. 3) electrically connected to the first andsecond photoelectric conversion regions 110 a and 110 b, andinterconnection lines 212, 213, and 214 electrically connected to thelogic transistors. The electrical signals converted in the first andsecond photoelectric conversion regions 110 a and 110 b may besignal-processed in the interconnection layer 20. The interconnectionlines 212, 213, and 214 may be disposed in interlayer insulating layers222, 223, and 224 stacked on the first surface 100 a of thesemiconductor substrate 100. According to some embodiments of presentinventive concepts, the interconnection lines 212, 213, and 214 may bearranged regardless of arrangement of the first and second photoelectricconversion regions 110 a and 110 b. In other words, the interconnectionlines 212, 213, and 214 may cross over the first and secondphotoelectric conversion regions 110 a and 110 b.

The light transmission layer 30 may include color filters 303G, 303R,and 303B and micro lenses 307G, 307R, and 307B. The light transmissionlayer 30 may concentrate and filter incident light and may provide theconcentrated and filtered light to the photoelectric conversion layer10.

In more detail, the semiconductor substrate 100 may be a substrate inwhich an epitaxial layer having a first conductivity type (e.g., aP-type) may be formed on a bulk silicon substrate having the firstconductivity type. In some embodiments, due to a process ofmanufacturing an image sensor, the bulk silicon substrate may be removedto leave only the P-type epitaxial layer in the semiconductor substrate100. In some embodiments, the semiconductor substrate 100 may be a bulksemiconductor substrate including a well having the first conductivitytype. Alternatively, in some embodiments, the semiconductor substrate100 may include one of other various substrates such as an N-typeepitaxial layer, a bulk silicon substrate, and a silicon-on-insulator(SOI) substrate.

According to some embodiments of present inventive concepts, thesemiconductor substrate 100 may include a plurality of unit pixelregions PG1, PG2, PR, and PB defined by a first isolation structure 101.The first isolation structure 101 may be a device isolation layerdefining the unit pixel regions PG1, PG2, PR, and PB.

The plurality of unit pixel regions PG1, PG2, PR, and PB may be arrangedin a matrix form along a first direction D1 and a second direction D2intersecting the first direction D1. In some embodiments, the pluralityof unit pixel regions may include first to third pixel regions PG1, PG2,PR, and PB. Lights having wavelength bands that are different from eachother may be incident on the first to third pixel regions PG1, PG2, PR,and PB. For example, light of a first wavelength band may be incident onthe first pixel regions PG1 and PG2, and light of a second wavelengthband longer than the first wavelength band may be incident on the secondpixel regions PR. Light of a third wavelength band shorter than thefirst wavelength band may be incident on the third pixel regions PB. Forexample, green light may be incident on the first pixel regions PG1 andPG2, red light may be incident on the second pixel regions PR, and bluelight may be incident on the third pixel regions PB.

The first pixel regions PG1 and PG2 may be arranged along the firstdirection D1 and the second direction D2 and may be spaced apart fromeach other. Each of the second pixel regions PR may be disposed betweenthe first pixel regions PG1 adjacent to each other in the seconddirection D2 and between the first pixel regions PG2 adjacent to eachother in the first direction D1. Each of the third pixel regions PB maybe disposed between the first pixel regions PG2 adjacent to each otherin the second direction D2 and between the first pixel regions PG1adjacent to each other in the first direction D1. In addition, the thirdpixel region PB and the second pixel region PR may be arranged in adiagonal direction (e.g., a third direction D3).

The isolation structure 101 may impede/prevent photocharges, which aregenerated by light incident on each of the first to third pixel regionsPG1, PG2, PR, and PB, from being diffused into neighboring pixel regionsPG1, PG2, PR, and PB by random drift. In other words, the firstisolation structure 101 may reduce/prevent a crosstalk phenomenonbetween the first to third pixel regions PG1, PG2, PR, and PB.

The first isolation structure 101 may surround each of the first tothird pixel regions PG1, PG2, PR, and PB when viewed from a plan view.In more detail, the first isolation structure 101 may include firstportions P1 and second portions P2. The first portions P1 may extend inthe second direction D2 and may be spaced apart from each other in thefirst direction D1. The second portions P2 may extend in the firstdirection D1 and may be spaced apart from each other in the seconddirection D2. Each of the first to third pixel regions PG1, PG2, PR, andPB may be defined by a pair of the first portions P1 and a pair of thesecond portions P2.

The first isolation structure 101 may be formed of an insulatingmaterial of which a refractive index is lower than that of thesemiconductor substrate 100 (e.g., silicon). The first isolationstructure 101 may include one insulating layer or a plurality ofinsulating layers. For example, the first isolation structure 101 may beformed of a silicon oxide layer, a silicon nitride layer, an undopedpoly-silicon layer, air, or any combination thereof. In someembodiments, the first surface 100 a and/or the second surface 100 b ofthe semiconductor substrate 100 may be patterned to form a deep trench,and then, the isolation structure 101 may be formed by filling the deeptrench with an insulating material.

The first isolation structure 101 may extend from the second surface 100b of the semiconductor substrate 100 toward the first surface 100 a ofthe semiconductor substrate 100 when viewed from a cross-sectional view.However, the first isolation structure 101 may be vertically spacedapart from the first surface 100 a of the semiconductor substrate 100.In other words, the first isolation structure 101 may have a first depthd1 that may be smaller than a vertical thickness of the semiconductorsubstrate 100. In some embodiments, unlike FIGS. 7A to 7C, the firstisolation structure 101 may penetrate the semiconductor substrate 100.In other words, the first depth d1 of the first isolation structure 101may be substantially equal to the vertical thickness of thesemiconductor substrate 100. In some embodiments, the first isolationstructure 101 may vertically extend from the first surface 100 a of thesemiconductor substrate 100 toward the second surface 100 b of thesemiconductor substrate 100. Accordingly, the first isolation structure101 may optionally be vertically spaced apart from the second surface100 b of the semiconductor substrate 100.

A top surface of the first isolation structure 101 may have a firstwidth W1. Meanwhile, a width of the first isolation structure 101 maybecome progressively less (i.e., may be tapered) from the second surface100 b toward the first surface 100 a of the semiconductor substrate 100.Alternatively, unlike FIGS. 7A to 7C, the width of the first isolationstructure 101 may become progressively less (i.e., may be tapered) fromthe first surface 100 a toward the second surface 100 b of thesemiconductor substrate 100.

The first and second photoelectric conversion regions 110 a and 110 bmay be disposed in the semiconductor substrate 100 of each of the firstto third pixel regions PG1, PG2, PR, and PB. In other words, a pair ofphotoelectric conversion regions 110 a and 110 b may be disposed in eachof the pixel regions PG1, PG2, PR, and PB. Each of the first and secondphotoelectric conversion regions 110 a and 110 b may be a dopant regiondoped with dopants having a second conductivity type (e.g., an N-type)opposite to the first conductivity type of the semiconductor substrate100. In some embodiments, the first and second photoelectric conversionregions 110 a and 110 b may be adjacent to the first surface 100 a ofthe semiconductor substrate 100 and may be vertically spaced apart fromthe second surface 100 b of the semiconductor substrate 100. In moredetail, dopants of the second conductivity type may be ion-implanted tothe first surface 100 a of the semiconductor substrate 100 to form thefirst and second photoelectric conversion regions 110 a and 110 b. Adopant concentration of a region, adjacent to the first surface 100 a,of each of the first and second photoelectric conversion regions 110 aand 110 b may be different from a dopant concentration of anotherregion, adjacent to the second surface 100 b, of each of the first andsecond photoelectric conversion regions 110 a and 110 b. Thus, each ofthe first and second photoelectric conversion regions 110 a and 110 bmay have a potential gradient between the first surface 100 a and thesecond surface 100 b of the semiconductor substrate 100.

The semiconductor substrate 100 and the first and second photoelectricconversion regions 110 a and 110 b may constitute a pair of photodiodes.In other words, the photodiode may be formed by P-N junction of thesemiconductor substrate 100 having the first conductivity type and thefirst or second photoelectric conversion region 110 a or 110 b havingthe second conductivity type. Each of the first and second photoelectricconversion regions 110 a and 110 b forming the photodiodes may generateor accumulate photocharges in proportion to the intensity of incidentlight. In addition, each of the photodiodes may further include a P-typedopant region that is shallowly doped with P-type dopants at a surfaceof each of the first and second photoelectric conversion regions 110 aand 110 b.

In each of the pixel regions PG1, PG2, PR, and PB, a phase differencemay occur between an electrical signal outputted from the firstphotoelectric conversion region 110 a and an electrical signal outputtedfrom the second photoelectric conversion region 110 b. The image sensoraccording to some embodiments of present inventive concepts may comparephases of the electrical signals outputted from the pair of first andsecond photoelectric conversion regions 110 a and 110 b to correct afocus of an imaging apparatus.

In each of the first and third pixel regions PG1, PG2, and PB, a secondisolation structure 103 may be disposed between the first and secondphotoelectric conversion regions 110 a and 110 b. The second isolationstructure 103 may include a first portion 103 a extending in the seconddirection D2 and a second portion 103 b extending in the first directionD1 when viewed from a plan view. The first portion 103 a of the secondisolation structure 103 may intersect the first and second photoelectricconversion regions 110 a and 110 b in a plan view, and the secondportion 103 b of the second isolation structure 103 may be disposedbetween the first and second photoelectric conversion regions 110 a and110 b.

The second isolation structure 103 may extend from the second surface100 b of the semiconductor substrate 100 toward the first surface 100 aof the semiconductor substrate 100 when viewed from a cross-sectionalview. In other words, the second isolation structure 103 may have asecond depth d2 that may be smaller than the vertical thickness of thesemiconductor substrate 100. Moreover, according to some embodiments ofpresent inventive concepts, the second depth d2 may be substantiallyequal to the first depth d1 of the first isolation structure 101described above.

In addition, a top surface of the second isolation structure 103 mayhave a second width W2. Meanwhile, a width of the second isolationstructure 103 may become progressively less (i.e., may be tapered) fromthe second surface 100 b toward the first surface 100 a of thesemiconductor substrate 100. According to some embodiments of presentinventive concepts, the second width W2 may be substantially equal tothe first width W1 of the first isolation structure 101 described above.

In each of the first and third pixel regions PG1, PG2, and PB, the firstand second photoelectric conversion regions 110 a and 110 b may beisolated or separated from each other by the second portion 103 b of thesecond isolation structure 103. In other words, the first photoelectricconversion region 110 a may be surrounded by the second portion 103 b ofthe second isolation structure 103 and a portion of the first isolationstructure 101 in each of the first and third pixel regions PG1, PG2, andPB, and the second photoelectric conversion region 110 b may besurrounded by the second portion 103 b of the second isolation structure103 and another portion of the first isolation structure 101 in each ofthe first and third pixel regions PG1, PG2, and PB. In some embodiments,the first and second photoelectric conversion regions 110 a and 110 b ofeach of the first and third pixel regions PG1, PG2, and PB may be incontact with a sidewall of the first isolation structure 101 and asidewall of the second portion 103 b of the second isolation structure103.

In addition, in each of the first and third pixel regions PG1, PG2, andPB, a portion of the first photoelectric conversion region 110 a may bedisposed between the first portion 103 a of the second isolationstructure 103 and the first surface 100 a of the semiconductor substrate100. Likewise, a portion of the second photoelectric conversion region110 b may be disposed between the first portion 103 a of the secondisolation structure 103 and the first surface 100 a of the semiconductorsubstrate 100.

In some embodiments, the second surface 100 b of the semiconductorsubstrate 100 may be patterned to form a deep trench in thesemiconductor substrate 100, and the second isolation structure 103 maybe formed by filling the deep trench with an insulating material. Asdescribed above, the width of the second isolation structure 103 maybecome progressively less from the second surface 100 b toward the firstsurface 100 a of the semiconductor substrate 100. In addition, thesecond isolation structure 103 may be vertically spaced apart from thefirst surface 100 a of the semiconductor substrate 100. In someembodiments, the second isolation structure 103 may be formed bypatterning the first surface 100 a of the semiconductor substrate 100.Accordingly, the second isolation structure 103 may optionally bevertically spaced apart from the second surface 100 b of thesemiconductor substrate 100.

In some embodiments, the second isolation structure 103 may be formedsimultaneously with the first isolation structure 101, and thus thesecond isolation structure 103 may include the same insulating materialas the first isolation structure 101. In addition, the second isolationstructure 103 and the first isolation structure 101 may constitute onebody in the semiconductor substrate 100. The second isolation structure103 may be formed of an insulating material of which a refractive indexis lower than that of the semiconductor substrate 100. For example, thesecond isolation structure 103 may be formed of a silicon oxide layer, asilicon nitride layer, an undoped poly-silicon layer, air, or anycombination thereof. The second isolation structure 103 mayreduce/prevent crosstalk between the first and second photoelectricconversion regions 110 a and 110 b in each of the first and third pixelregions PG1, PG2, and PB. Thus, a phase difference between electricalsignals can be accurately detected in each of the first and third pixelregions PG1, PG2, and PB. In other words, an auto-focusingcharacteristic may be improved in each of the first and third pixelregions PG1, PG2, and PB.

Light incident on each of the first and third pixel regions PG1, PG2,and PB may be irregularly reflected by the second isolation structure103, and thus the irregularly reflected light may be incident on a pixelregion adjacent thereto in the first direction D1 and a pixel regionadjacent thereto in the second direction D2. However, since the secondisolation structure 103 includes the first portion 103 a and the secondportion 103 b intersecting each other, the amount of the light incidenton the pixel region of the first direction D1 may be substantially equalto the amount of the light incident on the pixel region of the seconddirection D2. Thus, it is possible to reduce a noise difference whichmay occur according to positions of the first pixel regions PG1 and PG2.

In each of the second pixel regions PR, an isolation dopant region 105may be disposed between the first and second photoelectric conversionregions 110 a and 110 b. The wavelength band of light incident on thesecond pixel region PR including the isolation dopant region 105 may belonger than the wavelength bands of lights incident on the first andthird pixel regions PG1, PG2, and PB. Thus, the isolation dopant region105 may have a different shape from the second isolation structure 103.If the second isolation structure 103 described above is instead appliedto the second pixel regions PR, long-wavelength light incident on thesecond pixel regions PR may be easily irregularly reflected by thesecond isolation structure 103. This irregularly reflected light maycause a crosstalk phenomenon between the second pixel regions PR and thefirst pixel regions PG1 and PG2 adjacent to the second pixel regions PR.

In more detail, the isolation dopant region 105 may have a linear shapeextending in the first direction D1 when viewed from a plan view. Theisolation dopant region 105 may be in contact with the first isolationstructure 101. In addition, the isolation dopant region 105 mayvertically extend from the second surface 100 b of the semiconductorsubstrate 100 toward the first surface 100 a of the semiconductorsubstrate 100 when viewed from a cross-sectional view. The firstphotoelectric conversion region 110 a may be surrounded by the isolationdopant region 105 and a portion of the first isolation structure 101 ineach of the second pixel regions PR, and the second photoelectricconversion region 110 b may be surrounded by the isolation dopant region105 and another portion of the first isolation structure 101 in each ofthe second pixel regions PR.

In some embodiments, the isolation dopant region 105 may be a dopantregion that is formed in the semiconductor substrate 100 and has thefirst conductivity type. In detail, the isolation dopant region 105 maybe formed by ion-implanting dopants of the first conductivity type intothe semiconductor substrate 100 of the second pixel regions PR. Forexample, the isolation dopant region 105 may be formed by ion-implantingthe dopants of the first conductivity type to the second surface 100 bof the semiconductor substrate 100. The isolation dopant region 105 maybe vertically spaced apart from the first surface 100 a of thesemiconductor substrate 100. In other words, the isolation dopant region105 may have a third depth d3 that may be smaller than the verticalthickness of the semiconductor substrate 100. Meanwhile, the third depthd3 may be substantially equal to or different from the first depth d1 ofthe first isolation structure 101 and the second depth d2 of the secondisolation structure 103.

Since the isolation dopant region 105 is the dopant region of the firstconductivity type, a potential barrier between the first and secondphotoelectric conversion regions 110 a and 110 b may impede/preventphotocharges generated in the first photoelectric conversion region 110a from flowing into the second photoelectric conversion region 110 band/or may impede/prevent photocharges generated in the secondphotoelectric conversion region 110 b from flowing into the firstphotoelectric conversion region 110 a. In addition, since the isolationdopant region 105 is formed of the same semiconductor material as thefirst and second photoelectric conversion regions 110 a and 110 b, lightincident on the second pixel regions PR may not be refracted andreflected by the isolation dopant region 105 extending in the firstdirection D1. In other words, irregularly reflected light incident onthe pixel region adjacent to the second pixel region PR in the seconddirection D2 may be reduced to decrease a crosstalk phenomenontherebetween. As a result, it is possible to reduce a noise differencewhich may occur according to positions of the first pixel regions PG1and PG2 adjacent to the second pixel region PR.

In each of the first to third pixel regions PG1, PG2, PR, and PB, afloating diffusion layer 120 may be disposed between the first andsecond photoelectric conversion regions 110 a and 110 b. The floatingdiffusion layer 120 may be formed by ion-implanting dopants of thesecond conductivity type to the first surface 100 a of the semiconductorsubstrate 100.

A first transfer gate electrode 201 a may be disposed on the firstsurface 100 a of the semiconductor substrate 100 between the firstphotoelectric conversion region 110 a and the floating diffusion layer120, and a second transfer gate electrode 201 b may be disposed on thefirst surface 100 a of the semiconductor substrate 100 between thesecond photoelectric conversion region 110 b and the floating diffusionlayer 120. A first interlayer insulating layer 221 may cover the firstand second transfer gate electrodes 201 a and 201 b. Second to fourthinterlayer insulating layers 222, 223, and 224 may be disposed on thefirst interlayer insulating layer 221.

The first to third color filters 303G, 303R, and 303B and the first tothird micro lenses 307G, 307R, and 307B may be disposed on the secondsurface 100 b of the semiconductor substrate 100. The first to thirdcolor filters 303G, 303R, and 303B may be disposed on the first to thirdpixel regions PG1, PG2, PR, and PB, respectively, and the first to thirdmicro lenses 307G, 307R, and 307B may be disposed on the first to thirdcolor filters 303G, 303R, and 303B, respectively. In addition, a firstplanarization layer 301 may be disposed between the second surface 100 bof the semiconductor substrate 100 and the color filters 303G, 303R, and303B, and a second planarization layer 305 may be disposed between thecolor filters 303G, 303R, and 303B and the micro lenses 307G, 307R, and307B.

The first to third color filters 303G, 303R, and 303B may include thegreen, red, and blue color filters described with reference to FIG. 4A,respectively. Alternatively, the first to third color filters 303G,303R, and 303B may have other colors such as cyan, magenta, and yellow.In some embodiments, the first color filters 303G having green colorsmay be disposed on the first pixel regions PG1 and PG2, the second colorfilters 303R having red colors may be disposed on the second pixelregions PR, and the third color filters 303B having blue colors may bedisposed on the third pixel regions PB.

The first to third micro lenses 307G, 307R, and 307B may have convexshapes to concentrate lights incident on the first to third pixelregions PG1, PG2, PR, and PB. Each of the first to third micro lenses307G, 307R, and 307B may overlap the pair of first and secondphotoelectric conversion regions 110 a and 110 b when viewed from a planview. In other words, a center of each of the first to third microlenses 307G, 307R, and 307B may be substantially aligned with a centerof each of the pixel regions PG1, PG2, PR, and PB.

Next, the second region R2 of FIG. 5A will be described in detail withreference to FIGS. 8, 9A, 9B, and 10. In the second region R2, thedescriptions to the same features as in the first region R1 may beomitted or mentioned briefly for the purpose of ease and convenience inexplanation. In other words, mainly differences between the secondregion R2 and the first region R1 will be described.

Referring to FIGS. 8, 9A, 9B, and 10, the second isolation structure 103may be shifted in the third direction D3 in each of the first and thirdpixel regions PG1, PG2, and PB. In other words, the second isolationstructure 103 of the second region R2 may be shifted in the thirddirection D3 as compared with the second isolation structure (see V103of FIG. 9B) of the first region R1 described above.

The words “shift” and “shifted,” as used herein, may refer to an offsetbetween two elements. For example, the two elements may not be alignedin a vertical direction (i.e., may not be centered on the same verticalaxis), as a vertical axis extending through the center of one of theelements may not be aligned with a vertical axis extending through thecenter of the other one of the elements. Accordingly, the term “center,”as used herein, may refer to a central/centered vertical axis.

The third direction D3 may be the direction in which the center of thesemiconductor substrate 100 is spaced apart from the second region R2.In some embodiments, a center C103 of the second isolation structure 103may be shifted from a center CPG2 of the first pixel region PG2 by afirst distance L1 in the third direction D3 when viewed from a planview. In some embodiments, a center C103 of the second isolationstructure 103 of the third pixel region PB may be shifted from a centerCPB of the third pixel region PB by a second distance L2 in the thirddirection D3 when viewed from a plan view. In some embodiments, thefirst distance L1 may be substantially equal to the second distance L2.On the contrary, in each of the second pixel regions PR, the isolationdopant region 105 may be disposed at a center of the second pixel regionPR.

Each of the first to third micro lenses 307G, 307R, and 307B may beshifted in the third direction D3. In some embodiments, a center C307Gof the first micro lens 307G may be shifted from the center CPG2 of thefirst pixel region PG2 by a third distance L3 in the third direction D3when viewed from a plan view. Thus, a portion of the first micro lens307G may vertically overlap a portion of the third pixel region PBadjacent to the first pixel region PG2. In some embodiments, a centerC307B of the third micro lens 307B may be shifted from the center CPB ofthe third pixel region PB by a fourth distance L4 in the third directionD3 when viewed from a plan view. In some embodiments, the third distanceL3 may be substantially equal to the fourth distance L4. In addition, insome embodiments, a center of the second micro lens 307R may be shiftedfrom the center of the second pixel region PR by a fifth distance in thethird direction D3, and the fifth distance may be substantially equal tothe third distance L3 and the fourth distance L4.

Referring again to FIGS. 5B and 9B, the second light LI2 incident on thesecond region R2 may have the second incident angle θ2 smaller than 90degrees. Thus, the second light LI2 transmitted through each of thefirst to third micro lenses 307G, 307R, and 307B of the second region R2may not be irradiated to the center of the pixel region PG1, PG2, PR, orPB of the second region R2. However, since each of the first to thirdmicro lenses 307G, 307R, and 307B of the second region R2 is shifted inthe third direction D3 in the image sensor according to some embodimentsof present inventive concepts, the second light LI2 may be irradiatedclose to the center of each of the pixel regions PG1, PG2, PR, and PB.In addition, since the second isolation structure 103 of each of thefirst and third pixel regions PG1, PG2, and PB is also shifted in thethird direction D3, the second light LI2 may be irradiated to the centerof the second isolation structure 103. Thus, the second light LI2 may beuniformly scattered on all sides by the second isolation structure 103.As a result, it is possible to reduce a noise difference which may occuraccording to positions of the first pixel regions PG1 and PG2.

FIGS. 11 and 12 are enlarged plan views of the region ‘M’ of FIG. 8 toillustrate image sensors according to some embodiments of presentinventive concepts. Referring to FIGS. 11 and 12, the descriptions tothe same technical features as in FIGS. 8, 9A, 9B, and 10 may be omittedor mentioned briefly for the purpose of ease and convenience inexplanation. In other words, mainly differences between FIGS. 11 and 12and FIGS. 8, 9A, 9B, and 10 will be described hereinafter.

Referring to FIG. 11, the third distance L3 corresponding to the shifteddistance of the first micro lens 307G may be different from the fourthdistance L4 corresponding to the shifted distance of the third microlens 307B. For example, the third distance L3 may be greater than thefourth distance L4. In addition, in some embodiments, the fifth distancecorresponding to the shifted distance of the second micro lens 307R maybe different from the third distance L3 and the fourth distance L4. Inother words, the fifth distance, the third distance L3, and the fourthdistance L4 may be different from each other.

Light of which wavelength bands are different from each other may beincident on the first to third pixel regions PG1, PG2, PR, and PB. Thus,refracting angles of the light respectively incident on the first tothird pixel regions may be different from each other. The shifteddistances of the first to third micro lenses 307G, 307R, and 307B may bedifferent from each other in consideration of the refracting angles ofthe first to third pixel regions.

Referring to FIG. 12, the first distance L1 by which the isolationstructure 103 of the first pixel region PG2 is shifted may be differentfrom the second distance L2 by which the second isolation structure 103of the third pixel region PB is shifted. For example, the first distanceL1 may be greater than the second distance L2.

Light of which wavelength bands are different from each other may beincident on the first to third pixel regions PG1, PG2, PR, and PB. Thus,refracting angles of the light respectively incident on the first tothird pixel regions may be different from each other. The shifteddistances of the first and third pixel regions PG1, PG2, and PB may bedifferent from each other in consideration of the refracting angles ofthe first and third pixel regions PG1, PG2, and PB.

FIGS. 13 to 18 are cross-sectional views illustrating image sensorsaccording to some embodiments of present inventive concepts. FIG. 13 isa cross-sectional view taken along the line II-IF of FIG. 8, FIG. 14 isa cross-sectional view taken along the line I-I′ of FIG. 6, and FIGS. 15to 18 are cross-sectional views taken along the lines II-IF of FIG. 6.With respect to FIGS. 13-18, the descriptions to the same technicalfeatures as in FIGS. 6, 7A to 7C, 8, 9A, 9B, and 10 may be omitted ormentioned briefly for the purpose of ease and convenience inexplanation. In other words, mainly differences between FIGS. 13-18 andFIGS. 6, 7A to 7C, 8, 9A, 9B, and 10 will be described hereinafter.

According to FIGS. 8 and 13, the first to third color filters 303G,303R, and 303B may be shifted in the third direction D3. For example,the second color filter 303R of the second region R2 according to someembodiments may be shifted in the third direction D3 as compared withthe second color filter (see V303R of FIG. 13) of the first region R1described above.

As described above with reference to FIGS. 5B and 9B, the second lightLI2 incident on the second region R2 may not be irradiated to the centerof each of the pixel regions PG1, PG2, PR, and PB. Thus, the first tothird color filters 303G, 303R, and 303B may be shifted in the thirddirection D3 to irradiate the second light LI2 close to the center ofeach of the first to third color filters 303G, 303R, and 303B.

According to FIGS. 6 and 14, the first width W1 of the top surface ofthe first isolation structure 101 may be greater than the second widthW2 of the top surface of the second isolation structure 103. Inaddition, the first depth d1 of the first isolation structure 101 may begreater than the second depth d2 of the second isolation structure 103.These features of the first and second isolation structures 101 and 103may be applied to the second region R2.

According to FIGS. 6 and 15, in each of the second pixel regions PR, theisolation dopant region 105 may include a plurality of dopant regionsdoped with dopants of the first conductivity type. This isolation dopantregion 105 may be formed by repeatedly performing a plurality of ionimplantation processes using the dopants of the first conductivity type.Ion implantation depths of the dopants may be adjusted while repeatingthe ion implantation processes. In some embodiments, the isolationdopant region 105 may have a dopant concentration that is variedaccording to a distance from the second surface 100 b of thesemiconductor substrate 100. These features of the isolation dopantregion 105 may be applied to the second region R2.

According to FIGS. 6 and 16, the first isolation structure 101 mayinclude an isolation layer IL1 and a dopant layer ID covering a surfaceof the isolation layer ILL The dopant layer ID may have the firstconductivity type. The dopant layer ID may surround at least a portionof the isolation layer ILL The dopant layer ID may include dopants ofthe first conductivity type (e.g., a P-type). The dopant layer ID may bein direct contact with the semiconductor substrate 100 of the firstconductivity type. A concentration of the first conductivity typedopants in the dopant layer ID may be higher than a concentration of thefirst conductivity type dopants in the semiconductor substrate 100.Thus, the dopant layer ID may form a potential barrier around the firstand second photoelectric conversion regions 110 a and 110 b. As aresult, the dopant layer ID may reduce a dark current which may occur byelectron-hole pairs (EHPs) generated by surface defects of the deeptrench when an insulating layer is formed in the deep trench formed bypatterning the semiconductor substrate 100.

Like the first isolation structure 101, the second isolation structure103 may also include the isolation layer IL1 and the dopant layer ID. Inaddition, the features of the first and second isolation structures 101and 103 including the isolation layer IL1 and the dopant layer ID may beapplied to the second region R2.

According to FIGS. 6 and 17, the first isolation structure 101 mayinclude first and second isolation layers IL2 and IL3 having refractiveindexes different from each other. The first isolation layer IL2 may bein contact with the semiconductor substrate 100, and the secondisolation layer IL3 may be disposed in the first isolation layer IL2.Light obliquely incident on the first isolation structure 101 may berefracted at an interface between the first and second isolation layersIL2 and IL3 by a difference between the refractive indexes of the firstand second isolation layers IL2 and IL3. For example, the firstisolation layer IL2 may include a silicon oxide layer, a silicon nitridelayer, or a silicon oxynitride layer, and the second isolation layer IL3may include a silicon oxide layer, a silicon nitride layer, a siliconoxynitride layer, a poly-silicon layer, or a metal layer.

Like the first isolation structure 101, the second isolation structure103 may also include the first and second isolation layers IL2 and IL3.In addition, the features of the first and second isolation structures101 and 103 including the first and second isolation layers IL2 and IL3may be applied to the second region R2.

According to FIGS. 6 and 18, the first isolation structure 101 maypenetrate the semiconductor substrate 100. The first isolation structure101 may be formed by patterning the first surface 100 a of thesemiconductor substrate 100. Thus, the width of the first isolationstructure 101 may become progressively less from (i.e., may be taperedfrom) the first surface 100 a toward the second surface 100 b of thesemiconductor substrate 100. A bottom surface of the first isolationstructure 101 may have a third width W3. In some embodiments, the thirdwidth W3 may be greater than the second width W2 of the top surface ofthe second isolation structure 103. In addition, a depth of the firstisolation structure 101 may be greater than the depth of the secondisolation structure 103. These features of the first isolation structure101 described with reference to FIGS. 6 and 18 may be applied to thesecond region R2.

FIGS. 19 and 20 are plan views illustrating an image sensor according tosome embodiments of present inventive concepts. FIG. 19 is an enlargedplan view of the first region R1 of FIG. 5A, and FIG. 20 is an enlargedplan view of the second region R2 of FIG. 5A. FIG. 21 is across-sectional view taken along a line I-I′ FIG. 20. Referring to FIGS.19-21, the descriptions to the same technical features as in FIGS. 6, 7Ato 7C, 8, 9A, 9B, and 10 may be omitted or mentioned briefly for thepurpose of ease and convenience in explanation. In other words, mainlydifferences between FIGS. 19-21 and FIGS. 6, 7A to 7C, 8, 9A, 9B, and 10will be described hereinafter.

Referring to FIGS. 19 to 21, a third isolation structure 107 may bedisposed between the first and second photoelectric conversion regions110 a and 110 b in each of the third pixel regions PB. The thirdisolation structure 107 may have a linear shape extending in the firstdirection D1 when viewed from a plan view. The third isolation structure107 may be connected to the first isolation structure 101 to constituteone body in the semiconductor substrate 100. In other words, the thirdisolation structure 107 may have the same shape as the second isolationstructure 103 of FIGS. 6, 7A to 7C, 8, 9A, 9B, and 10, the first portion103 a of which is omitted. In addition, in the second region R2, acenter of the third isolation structure 107 may be shifted from thecenter of the third pixel region PB.

FIGS. 22 and 23 are plan views illustrating an image sensor according tosome embodiments of present inventive concepts. FIG. 22 is an enlargedplan view of the first region R1 of FIG. 5A, and FIG. 23 is an enlargedplan view of the second region R2 of FIG. 5A. FIG. 24 is across-sectional view taken along a line I-I′ FIG. 23. With respect toFIGS. 22-24, the descriptions to the same technical features as in FIGS.19 to 21 may be omitted or mentioned briefly for the purpose of ease andconvenience in explanation. In other words, mainly differences betweenFIGS. 22-24 and FIGS. 19 to 21 will be described hereinafter.

Referring to FIGS. 22 to 24, like the third pixel regions PB, the thirdisolation structure 107 may also be disposed in each of the first pixelregions PG1 and PG2. In other words, the third isolation structure 107extending in the first direction D1 may be disposed in each of the firstand third pixel regions PG1, PG2, and PB. In the second region R2, thecenter of the third isolation structure 107 may be shifted from thecenter of each of the first and third pixel regions PG1, PG2, and PB.

In the image sensor according to some embodiments of present inventiveconcepts, the micro lens and the isolation structure may be shifted inthe pixel region. Thus, it is possible to reduce the crosstalkphenomenon between the pixel regions adjacent to each other. As aresult, it is possible to reduce a noise difference between the pixelregions adjacent to each other.

The above-disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments, which fall withinthe true spirit and scope. Thus, to the maximum extent allowed by law,the scope is to be determined by the broadest permissible interpretationof the following claims and their equivalents, and shall not berestricted or limited by the foregoing detailed description.

1. (canceled)
 2. An image sensor comprising: a semiconductor substrateincluding a first pixel region in a first region and a second pixelregion in a second region; first and second device isolation layerssurrounding the first and second pixel regions, respectively, each ofthe first and second device isolation layers including a first portionand a second portion that extend in parallel to a first direction and athird portion and a fourth portion that extend in parallel to a seconddirection crossing the first direction, the first, second, third, andfourth portions defining four sides, respectively, of each of the firstand second pixel regions; a first photoelectric conversion element and asecond photoelectric conversion element in each of the first and secondpixel regions; a first isolation structure between the first and secondphotoelectric conversion elements in the first pixel region; and asecond isolation structure between the first and second photoelectricconversion elements in the second pixel region, wherein the firstisolation structure extends from a first point of the first portion ofthe first device isolation layer to a second point of the second portionof the first device isolation layer, wherein the second isolationstructure extends from a third point of the first portion of the seconddevice isolation layer to a fourth point of the second portion of thesecond device isolation layer, and wherein a position of the first pointof the first portion of the first device isolation layer is differentfrom a position of the third point of the first portion of the seconddevice isolation layer.
 3. The image sensor of claim 2, wherein thethird point is shifted relative to a center of the first portion of thesecond device isolation layer.
 4. The image sensor of claim 2, wherein afirst distance the first point is shifted from a center of the firstportion of the first device isolation layer is different from a seconddistance the third point is shifted from a center of the first portionof the second device isolation layer.
 5. The image sensor of claim 2,wherein a position of the second point in the second portion isdifferent from a position of the fourth point in the second portion. 6.The image sensor of claim 5, wherein the fourth point is shiftedrelative to a center of the second portion of the second deviceisolation layer.
 7. The image sensor of claim 5, wherein a firstdistance the second point is shifted from a center of the second portionof the first device isolation layer is different from a second distancethe fourth point is shifted from a center of the second portion of thesecond device isolation layer.
 8. The image sensor of claim 2, furthercomprising first and second micro lenses on the first and second pixelregions, respectively, wherein a center of the second micro lens isshifted from a center of the second pixel region when viewed in planview.
 9. The image sensor of claim 2, further comprising first andsecond color filters on the first and second pixel regions,respectively, wherein a center of the second color filter is shiftedfrom a center of the second pixel region when viewed in plan view. 10.The image sensor of claim 2, wherein the first device isolation layerand the first isolation structure are connected to each other toconstitute one body, and wherein the second device isolation layer andthe second isolation structure are connected to each other to constituteone body.
 11. The image sensor of claim 2, wherein a width of the firstdevice isolation layer is tapered from a first surface of thesemiconductor substrate toward a second surface of the semiconductorsubstrate, and wherein a width of the first isolation structure istapered from the first surface of the semiconductor substrate toward thesecond surface of the semiconductor substrate.
 12. The image sensor ofclaim 2, wherein a width of the first device isolation layer is taperedfrom a first surface of the semiconductor substrate toward a secondsurface of the semiconductor substrate, and wherein a width of the firstisolation structure is tapered from the second surface of thesemiconductor substrate toward the first surface of the semiconductorsubstrate.
 13. An image sensor comprising: a semiconductor substrateincluding a first pixel region and a second pixel region, each of thefirst and second pixel regions having first, second, third, and fourthsides; a first photoelectric conversion element and a secondphotoelectric conversion element in each of the first and second pixelregions; a first isolation structure between the first and secondphotoelectric conversion elements in the first pixel region; and asecond isolation structure between the first and second photoelectricconversion elements in the second pixel region, wherein the firstisolation structure extends from a first point of the first side of thefirst pixel region to a second point of the second side of the firstpixel region, the second side being opposite to the first side, whereinthe second isolation structure extends from a third point of the firstside of the second pixel region to a fourth point of the second side ofthe second pixel region, and wherein a position of the first point ofthe first side of the first pixel region is different from a position ofthe third point of the first side of the second pixel region.
 14. Theimage sensor of claim 13, wherein the third point is shifted relative toa center of the first side of the second pixel region.
 15. The imagesensor of claim 13, wherein a first distance the first point is shiftedfrom a center of the first side of the first pixel region is differentfrom a second distance the third point is shifted from a center of thefirst side of the second pixel region.
 16. The image sensor of claim 13,wherein a position of the second point of the second side is differentfrom a position of the fourth point of the second side.
 17. The imagesensor of claim 16, wherein the fourth point is shifted relative to acenter of the second side of the second pixel region.
 18. The imagesensor of claim 16, wherein a first distance the second point is shiftedfrom a center of the second side of the first pixel region is differentfrom a second distance the fourth point is shifted from a center of thesecond side of the second pixel region.
 19. An image sensor comprising:a semiconductor substrate including a first pixel region and a secondpixel region, each of the first and second pixel regions having first,second, third, and fourth sides; a first photoelectric conversionelement and a second photoelectric conversion element in each of thefirst and second pixel regions; a first isolation structure between thefirst and second photoelectric conversion elements in the first pixelregion; and a second isolation structure between the first and secondphotoelectric conversion elements in the second pixel region, whereinthe first isolation structure extends from a first point of the firstside of the first pixel region to a second point of the second side ofthe first pixel region, the second side being opposite to the firstside, wherein the second isolation structure extends from a third pointof the first side of the second pixel region to a fourth point of thesecond side of the second pixel region, and wherein a first distancefrom an intersection of the first side and the third side of the firstpixel region to the first point of the first side of the first pixelregion is different from a second distance from an intersection of thefirst side and the third side of the second pixel region to the thirdpoint of the first side of the second pixel region.
 20. The image sensorof claim 19, wherein a third distance from an intersection of the secondside and the third side of the first pixel region to the second point ofthe second side of the first pixel region is different from anintersection of the second side and the third side of the second pixelregion to the fourth point of the second side of the second pixelregion.
 21. The image sensor of claim 19, wherein the third point isshifted relative to a center of the first side of the second pixelregion, and wherein the fourth point is shifted relative to a center ofthe second side of the second pixel region.